Peroxide treated metallocene-based polyolefins with improved melt strength

ABSTRACT

Disclosed herein are ethylene-based polymers having low densities and narrow molecular weight distributions, but high melt strengths for blown film processing. Such polymers can be produced by peroxide-treating a metallocene-catalyzed resin.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 15/134,464, filed on Apr. 21, 2016, now U.S. Pat.No. 9,732,197, which is a divisional application of U.S. patentapplication Ser. No. 13/893,516, filed on May 14, 2013, now U.S. Pat.No. 9,346,897, the disclosures of which are incorporated herein byreference in their entirety.

BACKGROUND OF THE INVENTION

In various thick gauge film applications for linear low densitypolyethylene (LLDPE) resins, such as geomembrane applications, meltstrength for blown film processing and bubble stability can beimportant. Additionally, the density of the LLDPE resin can be reducedfor improved flexibility of the film, however the reduction in densitycan adversely affect the stiffness and maximum use temperature (e.g.,softening and/or melting temperature) of the film.

It would be beneficial to produce LLDPE resins having good melt strengthand sufficient flexibility after converting into a film, withoutsacrificing the maximum use temperature and stiffness of the film.Accordingly, it is to these ends that the present invention is directed.

SUMMARY OF THE INVENTION

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify required oressential features of the claimed subject matter. Nor is this summaryintended to be used to limit the scope of the claimed subject matter.

The present invention generally relates to ethylene polymers (e.g.,ethylene/α-olefin copolymers) which can have a ratio of Mw/Mn of lessthan or equal to about 5, a ratio of Mz/Mw of less than or equal toabout 2.3, and a zero-shear viscosity at 190° C. of greater than orequal to about 8×10⁴ Pa-sec. In further aspects, these ethylene polymerscan have a melt index in a range from 0 to about 2, and/or a ratio ofHLMI/MI in a range from about 15 to about 50, and/or a density in arange from about 0.895 to about 0.928 g/cm³, and/or a ratio of Mw/Mn ina range from about 2 to about 5, and/or a ratio of Mz/Mw in a range fromabout 1.5 to about 2.3, and/or a Mw in a range from about 75,000 toabout 250,000 g/mol, and/or a Mn in a range from about 10,000 to about70,000 g/mol, and/or a Mz in a range from about 175,000 to about 300,000g/mol, and/or a zero-shear viscosity at 190° C. in a range from about1×10⁵ to about 1×10⁶ Pa-sec, and/or a CY-a parameter at 190° C. in arange from about 0.08 to about 0.28, and/or from about 0.008 to about0.04 long chain branches (LCB) per 1000 total carbon atoms, and/or apeak melting point in a range from about 100 to about 120° C., and/or avicat softening temperature in a range from about 95 to about 110° C.,and/or a difference between the peak melting point and the vicatsoftening temperature of less than or equal to about 16° C., and/or areverse comonomer distribution. These ethylene polymers can be used toproduce various articles of manufacture, such as blown films and castfilms.

Processes for producing these ethylene polymers using a base resin and aperoxide compound also are disclosed herein. Typically, the base resincan be produced using a metallocene-based catalyst system and can becharacterized by a narrow molecular weight distribution.

Both the foregoing summary and the following detailed descriptionprovide examples and are explanatory only. Accordingly, the foregoingsummary and the following detailed description should not be consideredto be restrictive. Further, features or variations may be provided inaddition to those set forth herein. For example, certain aspects andembodiments may be directed to various feature combinations andsub-combinations described in the detailed description.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 presents a dynamic rheology plot (viscosity versus shear rate) at190° C. for the polymers of Examples 1-8.

FIG. 2 presents a tensile plot (stress versus strain) for the 10-milblown films of Examples 1-4 in the transverse direction (TD).

FIG. 3 presents a tensile plot (stress versus strain) for the 10-milblown films of Examples 1-4 in the machine direction (MD).

FIG. 4 presents a tensile plot (stress versus strain) for the 1-milblown films of Examples 1-4 in the transverse direction (TD).

DEFINITIONS

To define more clearly the terms used herein, the following definitionsare provided. Unless otherwise indicated, the following definitions areapplicable to this disclosure. If a term is used in this disclosure butis not specifically defined herein, the definition from the IUPACCompendium of Chemical Terminology, 2nd Ed (1997) can be applied, aslong as that definition does not conflict with any other disclosure ordefinition applied herein, or render indefinite or non-enabled any claimto which that definition is applied. To the extent that any definitionor usage provided by any document incorporated herein by referenceconflicts with the definition or usage provided herein, the definitionor usage provided herein controls.

Groups of elements are indicated using the numbering scheme indicated inthe version of the periodic table of elements published in Chemical andEngineering News, 63(5), 27, 1985. In some instances, a group ofelements can be indicated using a common name assigned to the group; forexample, alkali metals for Group 1 elements, alkaline earth metals forGroup 2 elements, transition metals for Group 3-12 elements, andhalogens or halides for Group 17 elements.

The terms “a,” “an,” “the,” etc., are intended to include pluralalternatives, e.g., at least one, unless otherwise specified. Forinstance, the disclosure of “an activator-support” or “a metallocenecompound” is meant to encompass one, or mixtures or combinations of morethan one, activator-support or metallocene compound, respectively,unless otherwise specified.

The term “polymer” is used herein generically to include olefinhomopolymers, copolymers, terpolymers, and so forth. A copolymer isderived from an olefin monomer and one olefin comonomer, while aterpolymer is derived from an olefin monomer and two olefin comonomers.Accordingly, “polymer” encompasses copolymers, terpolymers, etc.,derived from any olefin monomer and comonomer(s) disclosed herein.Similarly, an ethylene polymer would include ethylene homopolymers,ethylene copolymers, ethylene terpolymers, and the like. As an example,an olefin copolymer, such as an ethylene copolymer, can be derived fromethylene and a comonomer, such as 1-butene, 1-hexene, or 1-octene. Ifthe monomer and comonomer were ethylene and 1-hexene, respectively, theresulting polymer could be categorized an as ethylene/1-hexenecopolymer.

In like manner, the scope of the term “polymerization” includeshomopolymerization, copolymerization, terpolymerization, etc. Therefore,a copolymerization process could involve contacting one olefin monomer(e.g., ethylene) and one olefin comonomer (e.g., 1-hexene) to produce acopolymer.

The term “metallocene,” as used herein, describes compounds comprisingat least one η³ to η⁵-cycloalkadienyl-type moiety, wherein η³ toη⁵-cycloalkadienyl moieties include cyclopentadienyl ligands, indenylligands, fluorenyl ligands, and the like, including partially saturatedor substituted derivatives or analogs of any of these. Possiblesubstituents on these ligands may include H, therefore this inventioncomprises ligands such as tetrahydroindenyl, tetrahydrofluorenyl,octahydrofluorenyl, partially saturated indenyl, partially saturatedfluorenyl, substituted partially saturated indenyl, substitutedpartially saturated fluorenyl, and the like.

The terms “catalyst composition,” “catalyst mixture,” “catalyst system,”and the like, do not depend upon the actual product or compositionresulting from the contact or reaction of the initial components of thecatalyst composition/mixture/system, the nature of the active catalyticsite, or the fate of the co-catalyst, the metallocene compound(s), anyolefin monomer used to prepare a precontacted mixture, or the activator(e.g., activator-support), after combining these components. Therefore,the terms “catalyst composition,” “catalyst mixture,” “catalyst system,”and the like, encompass the initial starting components of thecomposition, as well as whatever product(s) may result from contactingthese initial starting components, and this is inclusive of bothheterogeneous and homogenous catalyst systems or compositions. The terms“catalyst composition,” “catalyst mixture,” “catalyst system,” and thelike, are used interchangeably throughout this disclosure.

The term “contact product” is used herein to describe compositionswherein the components are contacted together in any order, in anymanner, and for any length of time. For example, the components can becontacted by blending or mixing. Further, contacting of any componentcan occur in the presence or absence of any other component of thecompositions described herein. Combining additional materials orcomponents can be done by any suitable method. Further, the term“contact product” includes mixtures, blends, solutions, slurries,reaction products, and the like, or combinations thereof. Although“contact product” can include reaction products, it is not required forthe respective components to react with one another. Similarly, the term“contacting” is used herein to refer to materials which can be blended,mixed, slurried, dissolved, reacted, treated, or otherwise contacted insome other manner.

Although any methods, devices, and materials similar or equivalent tothose described herein can be used in the practice or testing of theinvention, the typical methods, devices and materials are hereindescribed.

All publications and patents mentioned herein are incorporated herein byreference for the purpose of describing and disclosing, for example, theconstructs and methodologies that are described in the publications,which might be used in connection with the presently describedinvention. The publications discussed throughout the text are providedsolely for their disclosure prior to the filing date of the presentapplication. Nothing herein is to be construed as an admission that theinventors are not entitled to antedate such disclosure by virtue ofprior invention.

Applicants disclose several types of ranges in the present invention.When Applicants disclose or claim a range of any type, Applicants'intent is to disclose or claim individually each possible number thatsuch a range could reasonably encompass, including end points of therange as well as any sub-ranges and combinations of sub-rangesencompassed therein. For example, when the Applicants disclose or claima chemical moiety or compound having a certain number of carbon atoms,Applicants' intent is to disclose or claim individually every possiblenumber that such a range could encompass, consistent with the disclosureherein. For example, the disclosure that a compound is a C₃ to C₁₈olefin, or in alternative language, an olefin having from 3 to 18 carbonatoms, as used herein, refers to a compound that can be selectedindependently from an olefin having 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,14, 15, 16, 17, or 18 carbon atoms, as well as any range between thesetwo numbers (for example, a C₄ to C₁₀ olefin), and also including anycombination of ranges between these two numbers (for example, a C₃ to C₈and a C₁₂ to C₁₆ olefin).

Similarly, another representative example follows for the number-averagemolecular weight (Mn) of an ethylene polymer consistent with an aspectof this invention. By a disclosure that the Mn can be in a range fromabout 30,000 to about 70,000 g/mol, Applicants intend to recite that theMn can be equal to about 30,000, about 35,000, about 40,000, about45,000, about 50,000, about 55,000, about 60,000, about 65,000, or about70,000 g/mol. Additionally, the Mn can be within any range from about30,000 to about 70,000 (for example, from about 35,000 to about 65,000),and this also includes any combination of ranges between about 30,000and about 70,000 (for example, the Mn can be in a range from about30,000 to about 45,000, or from about 50,000 to about 65,000). Likewise,all other ranges disclosed herein should be interpreted in a mannersimilar to these two examples.

Applicants reserve the right to proviso out or exclude any individualmembers of any such group, including any sub-ranges or combinations ofsub-ranges within the group, that can be claimed according to a range orin any similar manner, if for any reason Applicants choose to claim lessthan the full measure of the disclosure, for example, to account for areference that Applicants may be unaware of at the time of the filing ofthe application. Further, Applicants reserve the right to proviso out orexclude any individual substituents, analogs, compounds, ligands,structures, or groups thereof, or any members of a claimed group, if forany reason Applicants choose to claim less than the full measure of thedisclosure, for example, to account for a reference that Applicants maybe unaware of at the time of the filing of the application.

As used herein, “MD” refers to the machine direction, and “CD” refers tothe cross direction. The cross direction also can be referred to hereinas the transverse direction (TD). Various polymer and film propertiesare discussed throughout this disclosure. Following is a listing ofthese properties and their corresponding analytical test procedures andconditions:

Melt index (MI, g/10 min) was determined in accordance with ASTM D1238condition F at 190° C. with a 2.16 Kg weight. High load melt index(HLMI, g/10 min) was determined in accordance with ASTM D1238 conditionE at 190° C. with a 21.6 Kg weight. Polymer density was determined ingrams per cubic centimeter (g/cc or g/cm³) on a compression moldedsample, cooled at about 15° C. per minute, and conditioned for about 40hours at 23° C. in accordance with ASTM D1505 and ASTM D4703.

Vicat Softening Temperature was determined in accordance with ASTM D1525(Loading 1, Rate A, ° C.). The peak melting point was determined usingDifferential Scanning calorimetry (DSC) as described in ASTM D3418 (2ndheat, ° C.) at a heating rate of 10° C./min.

Molecular weights and molecular weight distributions were obtained usinga PL 220 SEC high temperature chromatography unit (Polymer Laboratories)with trichlorobenzene (TCB) as the solvent, with a flow rate of 1mL/minute at a temperature of 145° C. BHT(2,6-di-tert-butyl-4-methylphenol) at a concentration of 0.5 g/L wasused as a stabilizer in the TCB. An injection volume of 200 μL was usedwith a nominal polymer concentration of 1.5 mg/mL. Dissolution of thesample in stabilized TCB was carried out by heating at 150° C. for 5hours with occasional, gentle agitation. The columns used were threePLgel Mixed A LS columns (7.8×300 mm) and were calibrated with a broadlinear polyethylene standard (Chevron Phillips Chemical Marlex BHB 5003)for which the molecular weight had been determined. Mn is number-averagemolecular weight, Mw is weight-average molecular weight, and Mz isz-average molecular weight.

Melt rheological characterizations were performed as follows.Small-strain (10%) oscillatory shear measurements were performed on aRheometrics Scientific, Inc. ARES rheometer using parallel-plategeometry. All rheological tests were performed at 190° C. The complexviscosity |η*| versus frequency (ω) data were then curve fitted usingthe modified three parameter Carreau-Yasuda (CY) empirical model toobtain the zero-shear viscosity—η₀, characteristic viscous relaxationtime—τ_(η), and the breadth parameter—a (the CY-a parameter). Thesimplified Carreau-Yasuda (CY) empirical model is as follows.

${{{\eta*(\omega)}} = \frac{\eta_{0}}{\lbrack {1 + ( {\tau_{\eta}\omega} )^{a}} \rbrack^{{({1 - n})}/a}}},$wherein: |η*(ω)|=magnitude of complex shear viscosity;

-   -   η₀=zero-shear viscosity;    -   τ_(η)=viscous relaxation time;    -   a=“breadth” parameter (CY-a parameter);    -   n=fixes the final power law slope, fixed at 2/11; and    -   ω=angular frequency of oscillatory shearing deformation.

Details of the significance and interpretation of the CY model andderived parameters may be found in: C. A. Hieber and H. H. Chiang,Rheol. Acta, 28, 321 (1989); C. A. Hieber and H. H. Chiang, Polym. Eng.Sci., 32, 931 (1992); and R. B. Bird, R. C. Armstrong and O. Hasseger,Dynamics of Polymeric Liquids, Volume 1, Fluid Mechanics, 2nd Edition,John Wiley & Sons (1987); each of which is incorporated herein byreference in its entirety.

The LCB levels in samples were calculated using the method of Janzen andColby (J. Mol. Struct., 485/486, 569 (1999)), from values of zero-shearviscosity, η₀ (estimated from Carreau-Yasuda model fitted to dynamicshear viscosity data), and measured values of Mw obtained using a DawnEOS multiangle light scattering detector (Wyatt). See Y. Yu, D. C.Rohlfing, G. R Hawley, and P. J. DesLauriers, Polymer Preprint, 44, 50,(2003). The zero-shear melt viscosity was obtained by fitting theCarreau-Yasuda equation to the experimental viscosity derived at 190° C.as a function of shear rate.

Comonomer distribution and short chain branching content can bedetermined as described by P. J. DesLauriers, D. C. Rohlfing, and E. T.Hsieh in Polymer, 43, 159 (2002), and in U.S. Pat. No. 8,114,946, thedisclosures of which are incorporated herein by reference in theirentirety.

The blown film samples were produced on a laboratory-scale blown filmline using typical linear low density polyethylene conditions (LLDPE) asfollows: 100 mm (4 inch) die diameter, 2.8 mm (0.110 inch) die gap, 37.5mm (1.5 inch) diameter single-screw extruder fitted with a barrier screwwith a Maddock mixing section at the end (L/D=24, 2.2:1 compressionratio), 70-115 RPM screw speed (about 20-27 kg/hr (45-60 lb/hr) outputrate), 2.5:1 blow up ratio (BUR), “in-pocket” bubble with a “freeze lineheight” (FLH) between 20-28 cm (8-11 inch), 190° C. (375° F.) barrel anddie set temperatures and 25 micron (1 mil) and 250 micron (10 mil) thickfilm. Cooling was accomplished with a Dual Lip air ring using ambient(laboratory) air at about 25° C. (75-80° F.). These particularprocessing conditions were chosen because the film properties soobtained are typically representative of those obtained from larger,commercial scale film blowing conditions.

Stress versus strain curves and other film properties (e.g., see TableIII) were performed in accordance with ASTM D882.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed generally to ethylene-based polymershaving a unique combination of polymer properties. Articles, such asblown and cast films, can be produced from these ethylene-based polymersand are suitable in a variety of end-use applications.

Ethylene Polymers

Generally, the polymers disclosed herein are ethylene-based polymers, orethylene polymers, encompassing homopolymers of ethylene as well ascopolymers, terpolymers, etc., of ethylene and at least one olefincomonomer. Comonomers that can be copolymerized with ethylene often canhave from 3 to 20 carbon atoms in their molecular chain. For example,typical comonomers can include, but are not limited to, propylene,1-butene, 2-butene, 3-methyl-1-butene, isobutylene, 1-pentene,2-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 2-hexene,3-hexene, 3-ethyl-1-hexene, 1-heptene, 2-heptene, 3-heptene, the fournormal octenes (e.g., 1-octene), the four normal nonenes, the fivenormal decenes, and the like, or mixtures of two or more of thesecompounds. In an aspect, the olefin comonomer can comprise a C₃-C₁₈olefin; alternatively, the olefin comonomer can comprise a C₃-C₁₀olefin; alternatively, the olefin comonomer can comprise a C₄-C₁₀olefin; alternatively, the olefin comonomer can comprise a C₃-C₁₀α-olefin; or alternatively, the olefin comonomer can comprise a C₄-C₁₀α-olefin.

According to another aspect of this invention, the olefin monomer cancomprise ethylene, and the olefin comonomer can include, but is notlimited to, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene,1-octene, and the like, or combinations thereof. In yet another aspect,the comonomer can comprise 1-butene, 1-hexene, 1-octene, or anycombination thereof. In still another aspect, the comonomer can comprise1-butene; alternatively, 1-hexene; or alternatively, 1-octene.Typically, the amount of the comonomer, based on the total weight ofmonomer (ethylene) and comonomer, can be in a range from about 0.01 toabout 40 wt. %, from about 0.1 to about 35 wt. %, from about 0.5 toabout 30 wt. %, from about 1 to about 20 wt. %, from about 2 to about 18wt. %, or from about 3 to about 15 wt. %.

In some aspects, the ethylene polymer of this invention can be anethylene/α-olefin copolymer. For example, the ethylene polymer can be anethylene/1-butene copolymer, an ethylene/1-hexene copolymer, or anethylene/l-octene copolymer. In particular aspects contemplated herein,the ethylene polymer can be an ethylene/1-hexene copolymer.

An illustrative and non-limiting example of an ethylene polymer of thepresent invention can have a ratio of Mw/Mn of less than or equal toabout 5, a ratio of Mz/Mw of less than or equal to about 2.3, and azero-shear viscosity at 190° C. of greater than or equal to about 8×10⁴Pa-sec. Another illustrative and non-limiting example of an ethylenepolymer of the present invention can have a ratio of Mw/Mn in a rangefrom about 2 to about 5, a ratio of Mz/Mw in a range from about 1.5 toabout 2.3, and a zero-shear viscosity at 190° C. in a range from about8×10⁴ to about 2×10⁶ Pa-sec. Yet another illustrative and non-limitingexample of an ethylene polymer of the present invention can have a ratioof Mw/Mn in a range from about 2.1 to about 3.5, a ratio of Mz/Mw in arange from about 1.5 to about 2.2, and a zero-shear viscosity at 190° C.in a range from about 1×10⁵ to about 1×10⁶ Pa-sec. These illustrativeand non-limiting examples of ethylene polymers consistent with thepresent invention also can have any of the polymer properties listedbelow and in any combination.

Ethylene polymers in accordance with some aspects of this inventiongenerally can have a melt index (MI) from 0 to about 10 g/10 min. MI'sin the range from 0 to about 5 g/10 min, from 0 to about 2 g/10 min, orfrom 0 to about 1 g/10 min, are contemplated in other aspects of thisinvention. For example, a polymer of the present invention can have a MIin a range from about 0.05 to about 2, from about 0.05 to about 1, fromabout 0.05 to about 0.8, from about 0.1 to about 1, from about 0.1 toabout 0.8, from about 0.15 to about 1, or from about 0.15 to about 0.75g/10 min.

Ethylene polymers in accordance with this invention can have a ratio ofHLMI/MI of greater than about 5; alternatively, greater than about 10;alternatively, greater than about 15; or alternatively, greater thanabout 25. Suitable ranges for HLMI/MI can include, but are not limitedto, from about 10 to about 60, from about 15 to about 50, from about 20to about 50, from about 20 to about 45, from about 20 to about 40, orfrom about 25 to about 35, and the like.

The densities of ethylene-based copolymers disclosed herein often areless than about 0.930 g/cm³. In one aspect of this invention, thedensity of an ethylene copolymer can be less than about 0.928, less thanabout 0.925, or less than about 0.92 g/cm³. Yet, in another aspect, thedensity can be in a range from about 0.895 to about 0.928 g/cm³, suchas, for example, from about 0.90 to about 0.925 g/cm³, from about 0.905to about 0.925 g/cm³, or from about 0.91 to about 0.92 g/cm³.

Ethylene polymers consistent with various aspects of the presentinvention generally can have a narrow molecular weight distribution, andoften with weight-average molecular weights (Mw's) in a range from about75,000 to about 250,000 g/mol, from about 85,000 to about 200,000 g/mol,from about 90,000 to about 150,000 g/mol, from about 100,000 to about150,000 g/mol, from about 85,000 to about 140,000 g/mol, or from about100,000 to about 175,000 g/mol, and the like. Likewise, suitablenon-limiting ranges of the number-average molecular weight (Mn) caninclude from about 7,000 to about 70,000 g/mol, from about 10,000 toabout 70,000 g/mol, from about 25,000 to about 70,000 g/mol, from about30,000 to about 70,000 g/mol, or from about 35,000 to about 65,000g/mol, and the like. Further, suitable ranges for the z-averagemolecular weight (Mz) can include, for instance, from about 175,000 toabout 350,000 g/mol, from about 175,000 to about 300,000 g/mol, fromabout 200,000 to about 350,000 g/mol, from about 200,000 to about300,000 g/mol, from about 210,000 to about 290,000 g/mol, or from about225,000 to about 275,000 g/mol, and the like.

The ratio of Mw/Mn, or the polydispersity index, for the polymers ofthis invention often can be less than or equal to about 5, less than orequal to about 4.5, less than or equal to about 3.5, or less than orequal to about 3. In some aspects disclosed herein, the ratio of Mw/Mncan be in a range from about 2 to about 5, from about 2 to about 4, orfrom about 2 to about 3.5. In other aspects, the ratio of Mw/Mn can bein a range from about 2 to about 3, from about 2.1 to about 3.5, fromabout 2.1 to about 3, from about 2.1 to about 2.8, or from about 2.1 toabout 2.7.

The ratio of Mz/Mw for the polymers of this invention often can lessthan or equal to about 2.5, less than or equal to about 2.4, less thanor equal to about 2.3, or less than or equal to about 2.2. For example,the Mz/Mw ratio can be in a range from about 1.5 to about 2.4, fromabout 1.5 to about 2.3, from about 1.5 to about 2.2, from about 1.5 toabout 2.1, or from about 1.5 to about 2.

Generally, ethylene polymers consistent with aspects of the presentinvention have levels of long chain branches (LCB) per 1000 total carbonatoms in a range from about 0.008 to about 0.04, from about 0.009 toabout 0.035, or from about 0.01 to about 0.03 LCB per 1000 total carbonatoms. In some aspects, the number of LCB per 1000 total carbon atomscan be in a range from about 0.008 to about 0.035, from about 0.01 toabout 0.025, or from 0.012 to about 0.022 LCB per 1000 total carbonatoms.

Ethylene copolymers described herein can, in some aspects, have areverse comonomer distribution, i.e., a short chain branch content thatgenerally increases as molecular weight increases, for example, thehigher molecular weight components of the polymer generally have highercomonomer incorporation than the lower molecular weight components.Typically, there is increasing comonomer incorporation with increasingmolecular weight. For instance, the number of short chain branches(SCB's) per 1000 total carbon atoms can be greater at Mw than at Mn. Inone aspect, the ratio of the number of short chain branches (SCB) per1000 total carbon atoms of the polymer at Mw to the number of SCB per1000 total carbon atoms of the polymer at Mn can be in a range fromabout 1.1:1 to about 5:1, or alternatively, in a range from about 1.5:1to about 4:1.

In some aspects, ethylene polymers described herein can have azero-shear viscosity at 190° C. of greater than or equal to about 8×10⁴Pa-sec, or greater than or equal to about 1×10⁵ Pa-Sec. While notwishing to be bound by theory, Applicants believe that a higherzero-shear viscosity may correlate with a higher polymer melt strength(e.g., better bubble stability in blown film). Suitable ranges for thezero-shear viscosity can include, but are not limited to, from about8×10⁴ to about 2×10⁶, from about 1×10⁵ to about 2×10⁶, from about 1×10⁵to about 1×10⁶, from about 1×10⁵ to about 8×10⁵, or from about 1×10⁵ toabout 5×10⁵ Pa-sec.

In some aspects, the ethylene polymer can have a CY-a parameter at 190°C. in a range from about 0.08 to about 0.28, from about 0.09 to about0.25, from about 0.1 to about 0.25, from about 0.1 to about 0.22, fromabout 0.08 to about 0.18, from about 0.1 to about 0.2, or from about 0.1to about 0.18.

The peak melting point of the ethylene polymer (2nd heat, DSC) often canbe less than or equal to about 125° C., and more often, less than orequal to about 120° C. For instance, the peak melting point of theethylene polymer can be in a range from about 100 to about 120° C., fromabout 105 to about 120° C., or from about 110 to about 120° C.

The vicat softening temperature of the ethylene polymer often can be atleast about 90° C., and more often, at least about 95° C. For instance,the vicat softening temperature of the ethylene polymer can be in arange from about 100 to about 120° C., from about 100 to about 110° C.,from about 95 to about 110° C., or from about 95 to about 105° C.

Generally, the difference (or delta) between the peak melting point andthe vicat softening temperature of the ethylene polymer can be less thanor equal to about 20° C., such as, for instance, less than or equal toabout 18° C., less than or equal to about 16° C., or less than or equalto about 14° C.

Consistent with aspects of the present invention, the ethylene polymercan be produced from a base resin (discussed hereinbelow) via a processcomprising contacting the base resin with a peroxide compound at atemperature sufficient to generate peroxide groups at about 10 to about50 ppm of peroxide groups based on the weight of the base resin. In someaspects, the amount of peroxide groups in the peroxide compound, basedon the weight of the base resin, can be in a range from about 10 toabout 45 ppm, from about 15 to about 50 ppm, from about 15 to about 45ppm, from about 20 to about 50 ppm, from about 20 to about 45 ppm, fromabout 25 to about 50 ppm, or from about 25 to about 45 ppm.

The peroxide compound can be any compound containing one or moreperoxide (O—O) groups, suitable examples of which can include, but arenot limited to, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, dicumylperoxide, t-butyl cumyl peroxide,n-butyl-4,4′-di(t-butylperoxy)valerate, and the like.

In an aspect, the step of contacting the base resin with the peroxidecompound can comprise melt processing a blend (or mixture) of the baseresin and the peroxide compound at any suitable melt processingtemperature, such as, for example, a temperature in a range from about120 to about 300° C., a temperature in a range from about 150 to about250° C., a temperature in a range from about 175 to about 225° C., andso forth. The appropriate temperature may depend upon the composition ofthe peroxide compound and the temperature at which it liberates peroxidegroups. Prior to contacting the peroxide compound, the base resin can bein any suitable form including, for example, fluff, powder, granulate,pellet, solution, slurry, emulsion, and the like. Similarly, theperoxide compound can be in solid form, in solution, or in a slurry. Oneparticular method uses a resin-based masterbatch of the peroxidecompound, and contacts the base resin after it has been melted.

The present invention is not limited to any particular method ofcontacting and melt processing the base resin and the peroxide compound.Various methods of mixing and/or compounding can be employed, as wouldbe recognized by those of skill in the art. In one aspect, the meltprocessing of the base resin and the peroxide compound can be performedin a twin screw extrusion system. In another aspect, the melt processingof the base resin and the peroxide compound can be performed in a singlescrew extrusion system.

Films and Articles

Articles of manufacture can be formed from, and/or can comprise, theethylene polymers of this invention and, accordingly, are encompassedherein. For example, articles which can comprise ethylene polymers ofthis invention can include, but are not limited to, an agriculturalfilm, an automobile part, a bottle, a drum, a fiber or fabric, a foodpackaging film or container, a food service article, a fuel tank, ageomembrane, a household container, a liner, a molded product, a medicaldevice or material, a pipe, a sheet or tape, a toy, and the like.Various processes can be employed to form these articles. Non-limitingexamples of these processes include injection molding, blow molding,rotational molding, film extrusion, sheet extrusion, profile extrusion,thermoforming, and the like. Additionally, additives and modifiers areoften added to these polymers in order to provide beneficial polymerprocessing or end-use product attributes. Such processes and materialsare described in Modern Plastics Encyclopedia, Mid-November 1995 Issue,Vol. 72, No. 12; and Film Extrusion Manual—Process, Materials,Properties, TAPPI Press, 1992; the disclosures of which are incorporatedherein by reference in their entirety.

In some aspects, the article produced from and/or comprising an ethylenepolymer of this invention is a film product. For instance, the film canbe a blown film or a cast film that is produced from and/or comprises anethylene polymer disclosed herein. Such films also can contain one ormore additives, non-limiting examples of which can include anantioxidant, an acid scavenger, an antiblock additive, a slip additive,a colorant, a filler, a processing aid, a UV inhibitor, and the like, aswell as combinations thereof.

Applicants also contemplate a method for making a film (e.g., a blownfilm, a cast film, etc.) comprising any ethylene polymer disclosedherein. For instance, the method can comprise melt processing theethylene polymer through a die to form the film. Suitably, the die canbe configured based on the film to be produced, for example, an annularblown film die to produce a blown film, a slot or cast film die toproduce a cast film, and so forth. Moreover, any suitable means of meltprocessing can be employed, although extrusion typically can beutilized. As above, additives can be combined with the ethylene polymerin the melt processing step (extrusion step), such as antioxidants, acidscavengers, antiblock additives, slip additives, colorants, fillers,processing aids, UV inhibitors, and the like, as well as combinationsthereof.

Films disclosed herein, whether cast or blown, can be any thickness thatis suitable for the particular end-use application, and often, the filmthickness can be in a range from about 0.5 to about 250 mils, or fromabout 1 to about 200 mils. Thicker films generally are employed ingeomembrane and related applications, and these films can havethicknesses in a range from about 10 to about 200 mils, from about 20 toabout 200 mils, from about 25 to about 150 mils, from about 30 to about120 mils, or from about 40 to about 100 mils.

In an aspect and unexpectedly, the films disclosed herein, whether castor blown, can have a generally non-distinct yield point in thetransverse direction (TD). While not wishing to be bound by theory,Applicants believe that thick films with a non-distinct yield point maybe less susceptible to thinning or failures in creased and/or foldedareas. One measure of the non-distinct yield point is the ratio of themaximum stress at a strain of less than 40% to the maximum stress at astrain in the 40% to 60% range, in a stress versus strain curve in theTD for a 10-mil film (e.g., a blown film, a cast film). In some aspects,the ratio can be less than or equal to 1, less than or equal to about0.99, or less than or equal to about 0.98, while in other aspects, theratio can be in a range from about 0.85 to 1, from about 0.9 to about0.99, or from about 0.9 to about 0.98. In another aspect, the generallynon-distinct yield point can be measured by the ratio of the maximumstress at a strain of less than 40% to the maximum stress at a strain inthe 40% to 60% range, in a stress versus strain curve in the TD for a1-mil film (e.g., a blown film, a cast film). In some aspects, the ratiocan be less than or equal to 1.1, less than or equal to about 1, lessthan or equal to about 0.99, or less than or equal to about 0.98, whilein other aspects, the ratio can be in a range from about 0.85 to 1.1,from about 0.9 to about 1, or from about 0.9 to about 0.99.

Also unexpectedly, in a stress versus strain curve in the transversedirection (TD) for a 10-mil film, the slope is not negative in the 25%to 50% strain range in some aspects of this invention. In furtheraspects, and unexpectedly, in a stress versus strain curve in thetransverse direction (TD) for a 10-mil film, the stress at 50% straincan be greater than the stress at the yield point. Likewise, in a stressversus strain curve in the transverse direction (TD) for a 1-mil film,the slope is not negative in the 25% to 30% strain range in some aspectsof this invention. Moreover, and unexpectedly, in a stress versus straincurve in the transverse direction (TD) for a 1-mil film, the ratio ofthe stress at 30% strain to the stress at the yield point can be greaterthan or equal to 0.9, for example, greater than or equal to about 0.95,greater than or equal to about 1, in a range from 0.9 to about 1.2, in arange from 0.9 to about 1.1, in a range from about 0.95 to about 1.2, ina range from about 0.95 to about 1.1, and the like. For these film(stress-strain) evaluations of 1-mil and 10-mil films, the equipment andfabrication conditions used are as described herein above.

Base Resins

Generally, the base resin used to produce the ethylene polymer can beany homopolymer of ethylene or copolymer, terpolymer, etc., of ethyleneand at least one olefin comonomer disclosed hereinabove for the ethylenepolymer. Thus, the base resin can be an ethylene/α-olefin copolymer,such as an ethylene/1-butene copolymer, an ethylene/1-hexene copolymer,or an ethylene/1-octene copolymer. Typically, for example, if the baseresin is an ethylene/1-hexene copolymer, then the ethylene polymerproduced from the base resin also is an ethylene/1-hexene copolymer,although mixtures and combinations of various types of homopolymers andcopolymers can be used.

The base resin used to produce ethylene polymers in accordance with someaspects of this invention generally can have a melt index (MI) from 0 toabout 5 g/10 min. MI's in the range from 0 to about 2 g/10 min, fromabout 0.25 to about 5 g/10 min, or from about 0.25 to about 2 g/10 min,are contemplated in other aspects of this invention. For example, a baseresin can have a MI in a range from about 0.25 to about 2.5, from about0.5 to about 2.5, from about 0.5 to about 2, from about 0.5 to about1.75, from about 0.5 to about 1.5, from about 0.75 to about 2, or fromabout 0.75 to about 1.75 g/10 min.

The base resin used to produce ethylene polymers in accordance with thisinvention can have a ratio of HLMI/MI of greater than about 5;alternatively, greater than about 8; alternatively, greater than about10; or alternatively, greater than about 15. Suitable ranges for HLMI/MIcan include, but are not limited to, from about 8 to about 35, fromabout 10 to about 35, from about 10 to about 30, from about 10 to about25, from about 10 to about 20, or from about 15 to about 30, and thelike.

The densities of copolymer base resin used to produce ethylenecopolymers disclosed herein often are less than about 0.930 g/cm³. Inone aspect of this invention, the density of a base resin can be lessthan about 0.928, less than about 0.925, or less than about 0.92 g/cm³.Yet, in another aspect, the density can be in a range from about 0.895to about 0.928 g/cm³, such as, for example, from about 0.90 to about0.925 g/cm³, from about 0.905 to about 0.925 g/cm³, or from about 0.91to about 0.92 g/cm³.

Base resins consistent with various aspects of the present inventiongenerally can have a narrow molecular weight distribution, and oftenwith weight-average molecular weights (Mw's) in a range from about75,000 to about 250,000 g/mol, from about 85,000 to about 200,000 g/mol,from about 90,000 to about 150,000 g/mol, from about 100,000 to about150,000 g/mol, from about 85,000 to about 140,000 g/mol, or from about100,000 to about 175,000 g/mol, and the like. Likewise, suitablenon-limiting ranges of the number-average molecular weight (Mn) caninclude from about 7,000 to about 70,000 g/mol, from about 10,000 toabout 70,000 g/mol, from about 25,000 to about 70,000 g/mol, from about30,000 to about 70,000 g/mol, or from about 35,000 to about 65,000g/mol, and the like. Further, suitable ranges for the z-averagemolecular weight (Mz) can include, for instance, from about 165,000 toabout 350,000 g/mol, from about 165,000 to about 300,000 g/mol, fromabout 175,000 to about 300,000 g/mol, from about 175,000 to about275,000 g/mol, from about 200,000 to about 300,000 g/mol, or from about200,000 to about 290,000 g/mol, and the like.

The ratio of Mw/Mn, or the polydispersity index, for the base resins ofthis invention often can less than or equal to about 5, less than orequal to about 4.5, less than or equal to about 3.5, or less than orequal to about 3. In some aspects disclosed herein, the ratio of Mw/Mncan be in a range from about 2 to about 5, from about 2 to about 4, orfrom about 2 to about 3.5. In other aspects, the ratio of Mw/Mn can bein a range from about 2 to about 3, from about 2.1 to about 3.5, fromabout 2.1 to about 3, from about 2.1 to about 2.8, or from about 2.1 toabout 2.7.

The ratio of Mz/Mw for the base resins of this invention often can lessthan or equal to about 2.5, less than or equal to about 2.4, less thanor equal to about 2.3, or less than or equal to about 2.2. For example,the Mz/Mw ratio can be in a range from about 1.5 to about 2.4, fromabout 1.5 to about 2.3, from about 1.5 to about 2.2, from about 1.5 toabout 2.1, or from about 1.5 to about 2.

Generally, base resins consistent with aspects of the present inventioncan have low levels of long chain branches (LCB) per 1000 total carbonatoms, such as less than about 0.008 LCB per 1000 total carbon atoms,but greater than zero. In some aspects, the number of LCB per 1000 totalcarbon atoms can less than about 0.006 LCB, less than about 0.005 LCB,or less than about 0.003 LCB, per 1000 total carbon atoms.

Base resins described herein can, in some aspects, have a reversecomonomer distribution, i.e., a short chain branch content thatgenerally increases as molecular weight increases, for example, thehigher molecular weight components of the polymer generally have highercomonomer incorporation than the lower molecular weight components.Typically, there is increasing comonomer incorporation with increasingmolecular weight. For instance, the number of short chain branches(SCB's) per 1000 total carbon atoms can be greater at Mw than at Mn. Inone aspect, the ratio of the number of short chain branches (SCB) per1000 total carbon atoms of the base resin at Mw to the number of SCB per1000 total carbon atoms of the polymer at Mn can be in a range fromabout 1.1:1 to about 5:1, or alternatively, in a range from about 1.5:1to about 4:1.

In some aspects, base resins described herein can have a zero-shearviscosity at 190° C. in a range from about 2×10³ Pa-sec to about 7×10⁴Pa-Sec. Suitable ranges for the zero-shear viscosity of the base resincan include, but are not limited to, from about 2×10³ to about 5×10⁴,from about 3×10³ to about 5×10⁴, from about 2×10³ to about 2×10⁴, fromabout 3×10³ to about 2×10⁴, or from about 2×10³ to about 1×10⁴ Pa-sec.

In some aspects, the base resin can have a CY-a parameter at 190° C. ina range from about 0.4 to about 0.8, from about 0.5 to about 0.8, fromabout 0.4 to about 0.7, from about 0.5 to about 0.7, from about 0.45 toabout 0.75, from about 0.55 to about 0.75, or from about 0.55 to about0.7.

The peak melting point of the base resin (2nd heat, DSC) often can beless than or equal to about 125° C., and more often, less than or equalto about 120° C. For instance, the peak melting point of the base resincan be in a range from about 100 to about 120° C., from about 105 toabout 120° C., or from about 110 to about 120° C.

The vicat softening temperature of the base resin often can be at leastabout 90° C., and more often, at least about 95° C. For instance, thevicat softening temperature of the base resin can be in a range fromabout 100 to about 120° C., from about 100 to about 110° C., or fromabout 95 to about 105° C.

Generally, the difference (or delta) between the peak melting point andthe vicat softening temperature of the base resin can be less than orequal to about 20° C., such as, for instance, less than or equal toabout 18° C., less than or equal to about 16° C., or less than or equalto about 14° C.

Consistent with aspects of the present invention, the base resin can beproduced using a metallocene-based catalyst system. Thus, the base resincan be produced using a metallocene-based catalyst system containing anysuitable metallocene compound and any suitable activator (one or morethan one metallocene compound and one or more than one activator can beemployed). The metallocene compound can comprise, for example, atransition metal from Groups III, IV, V, or VI of the Periodic Table ofthe Elements, or a combination of two or more transition metals. Themetallocene compound can comprise chromium, titanium, zirconium,hafnium, vanadium, or a combination thereof, or can comprise titanium,zirconium, hafnium, or a combination thereof, in certain aspects.Accordingly, the metallocene compound can comprise titanium, orzirconium, or hafnium, either singly or in combination.

While not being limited thereto, the metallocene compound can comprisean unbridged metallocene compound in an aspect of this invention. Forinstance, the metallocene compound can comprise an unbridged zirconiumor hafnium based metallocene compound and/or an unbridged zirconiumand/or hafnium based dinuclear metallocene compound. In one aspect, themetallocene compound can comprise an unbridged zirconium or hafniumbased metallocene compound containing two cyclopentadienyl groups, twoindenyl groups, or a cyclopentadienyl and an indenyl group. In anotheraspect, the metallocene compound can comprise an unbridged zirconiumbased metallocene compound containing two cyclopentadienyl groups, twoindenyl groups, or a cyclopentadienyl and an indenyl group. Illustrativeand non-limiting examples of unbridged metallocene compounds (e.g., withzirconium or hafnium) that can be employed in catalyst systemsconsistent with aspects of the present invention are described in U.S.Pat. Nos. 7,226,886 and 7,619,047, the disclosures of which areincorporated herein by reference in their entirety.

In other aspects, the metallocene compound can comprise an unbridgedzirconium and/or hafnium based dinuclear metallocene compound. Forexample, the metallocene compound can comprise an unbridged zirconiumbased homodinuclear metallocene compound, or an unbridged hafnium basedhomodinuclear metallocene compound, or an unbridged zirconium and/orhafnium based heterodinuclear metallocene compound (i.e., a dinuclearcompound with two hafniums, or two zirconiums, or one zirconium and onehafnium). These and other suitable dinuclear compounds (bridged andunbridged) are described in U.S. Pat. Nos. 7,863,210, 7,919,639,8,012,900, and 8,080,681, the disclosures of which are incorporatedherein by reference in their entirety.

The metallocene compound can comprise a bridged metallocene compound,e.g., with titanium, zirconium, or hafnium. Accordingly, the metallocenecompound can comprise a bridged zirconium based metallocene compoundwith a fluorenyl group, and with no aryl groups on the bridging group,or a bridged zirconium based metallocene compound with acyclopentadienyl group and a fluorenyl group, and with no aryl groups onthe bridging group. Such bridged metallocenes, in some aspects, cancontain an alkenyl substituent (e.g., a terminal alkenyl) on thebridging group and/or on a cyclopentadienyl-type group (e.g., acyclopentadienyl group, a fluorenyl group, etc.).

In another aspect, the metallocene compound can comprise a bridgedzirconium or hafnium based metallocene compound with a fluorenyl group,and an aryl group on the bridging group. Thus, the metallocene compoundcan comprise a bridged zirconium or hafnium based metallocene compoundwith a cyclopentadienyl group and fluorenyl group, and an aryl group onthe bridging group; alternatively, a bridged zirconium based metallocenecompound with a fluorenyl group, and an aryl group on the bridginggroup; or alternatively, a bridged hafnium based metallocene compoundwith a fluorenyl group, and an aryl group on the bridging group. Inthese and other aspects, the aryl group on the bridging group can be aphenyl group. Optionally, these bridged metallocenes can contain analkenyl substituent (e.g., a terminal alkenyl) on the bridging groupand/or on a cyclopentadienyl-type group.

Illustrative and non-limiting examples of bridged metallocene compounds(e.g., with zirconium or hafnium) that can be employed in catalystsystems consistent with aspects of the present invention are describedin U.S. Pat. Nos. 7,041,617, 7,226,886, 7,517,939, 7,619,047, and8,329,834, the disclosures of which are incorporated herein by referencein their entirety.

In one aspect, the catalyst composition contains only one metallocenecompound, while in another aspect, the catalyst composition contains twoor more metallocene compounds. If two or more metallocene compounds areused, the relative amounts of each respective metallocene compound arenot restricted to any particular range. For instance, if the catalystcomposition contains two metallocene compounds, the weight ratio of thefirst metallocene catalyst component to the second metallocene catalystcomponent can be in a range of from about 1:100 to about 100:1, fromabout 1:50 to about 50:1, from about 1:25 to about 25:1, from about 1:20to about 20:1, from about 1:15 to about 15:1, from about 1:10 to about10:1, or from about 1:5 to about 5:1. Accordingly, suitable ranges forthe weight ratio of the first metallocene catalyst component to thesecond metallocene catalyst component can include, but are not limitedto, from about 1:4 to about 4:1, from about 1:3 to about 3:1, from about1:2 to about 2:1, from about 1:1.5 to about 1.5:1, from about 1:1.25 toabout 1.25:1, or from about 1:1.1 to about 1.1:1, and the like.

Typically, the metallocene-based catalyst system contains an activator.For example, the catalyst system can contain an activator-support, analuminoxane compound, an organoboron or organoborate compound, anionizing ionic compound, and the like, or any combination thereof. Thecatalyst system can contain one or more than one activator.

In one aspect, the catalyst system can comprise an aluminoxane compound,an organoboron or organoborate compound, an ionizing ionic compound, andthe like, or a combination thereof. Examples of such activators aredisclosed in, for instance, U.S. Pat. Nos. 3,242,099, 4,794,096,4,808,561, 5,576,259, 5,807,938, 5,919,983, and 8,114,946, thedisclosures of which are incorporated herein by reference in theirentirety. In another aspect, the catalyst system can comprise analuminoxane compound. In yet another aspect, the catalyst system cancomprise an organoboron or organoborate compound. In still anotheraspect, the catalyst system can comprise an ionizing ionic compound.

In other aspects, the catalyst system can comprise an activator-support,for example, an activator-support comprising a solid oxide treated withan electron-withdrawing anion. Examples of such materials are disclosedin, for instance, U.S. Pat. Nos. 7,294,599 and 7,601,665, thedisclosures of which are incorporated herein by reference in theirentirety.

The solid oxide used to produce the activator-support can compriseoxygen and one or more elements from Groups 2, 3, 4, 5, 6, 7, 8, 9, 10,11, 12, 13, 14, or 15 of the periodic table, or comprising oxygen andone or more elements from the lanthanide or actinide elements (see e.g.,Hawley's Condensed Chemical Dictionary, 11^(th) Ed., John Wiley & Sons,1995; Cotton, F. A., Wilkinson, G., Murillo, C. A., and Bochmann, M.,Advanced Inorganic Chemistry, 6^(th) Ed., Wiley-Interscience, 1999). Forinstance, the solid oxide can comprise oxygen and at least one elementselected from Al, B, Be, Bi, Cd, Co, Cr, Cu, Fe, Ga, La, Mn, Mo, Ni, Sb,Si, Sn, Sr, Th, Ti, V, W, P, Y, Zn, and Zr.

Accordingly, suitable examples of solid oxide materials that can be usedto form the activator-supports can include, but are not limited to,Al₂O₃, B₂O₃, BeO, Bi₂O₃, CdO, Co₃O₄, Cr₂O₃, CuO, Fe₂O₃, Ga₂O₃, La₂O₃,Mn₂O₃, MoO₃, NiO, P₂O₅, Sb₂O₅, SiO₂, SnO₂, SrO, ThO₂, TiO₂, V₂O₅, WO₃,Y₂O₃, ZnO, ZrO₂, and the like, including mixed oxides thereof, andcombinations thereof. This includes co-gels or co-precipitates ofdifferent solid oxide materials. The solid oxide can encompass oxidematerials such as alumina, “mixed oxides” thereof such assilica-alumina, and combinations and mixtures thereof. The mixed oxidessuch as silica-alumina can be single or multiple chemical phases withmore than one metal combined with oxygen to form the solid oxide.Examples of mixed oxides that can be used to form an activator-support,either singly or in combination, can include, but are not limited to,silica-alumina, silica-titania, silica-zirconia, alumina-titanic,alumina-zirconia, zinc-aluminate, alumina-boria, silica-boria,aluminophosphate-silica, titania-zirconia, and the like. The solid oxideused herein also can encompass oxide materials such as silica-coatedalumina, as described in U.S. Pat. No. 7,884,163, the disclosure ofwhich is incorporated herein by reference in its entirety.

Accordingly, in one aspect, the solid oxide can comprise silica,alumina, silica-alumina, silica-coated alumina, aluminum phosphate,aluminophosphate, heteropolytungstate, titania, zirconia, magnesia,boria, zinc oxide, any mixed oxide thereof, or any combination thereof.In another aspect, the solid oxide can comprise silica, alumina,titania, zirconia, magnesia, boria, zinc oxide, any mixed oxide thereof,or any combination thereof. In yet another aspect, the solid oxide cancomprise silica-alumina, silica-coated alumina, silica-titania,silica-zirconia, alumina-boria, or any combination thereof. In stillanother aspect, the solid oxide can comprise silica; alternatively,alumina; alternatively, silica-alumina; or alternatively, silica-coatedalumina.

The silica-alumina which can be used typically can have an aluminacontent from about 5 to about 95% by weight. In one aspect, the aluminacontent of the silica-alumina can be from about 5 to about 50%, or fromabout 8% to about 30%, alumina by weight. In another aspect, highalumina content silica-alumina compounds can be employed, in which thealumina content of these silica-alumina compounds typically can rangefrom about 60% to about 90%, or from about 65% to about 80%, alumina byweight. According to yet another aspect, the solid oxide component cancomprise alumina without silica, and according to another aspect, thesolid oxide component can comprise silica without alumina. Moreover, asprovided hereinabove, the solid oxide can comprise a silica-coatedalumina. The solid oxide can have any suitable surface area, porevolume, and particle size, as would be recognized by those of skill inthe art.

The electron-withdrawing component used to treat the solid oxide can beany component that increases the Lewis or Brønsted acidity of the solidoxide upon treatment (as compared to the solid oxide that is not treatedwith at least one electron-withdrawing anion). According to one aspect,the electron-withdrawing component can be an electron-withdrawing anionderived from a salt, an acid, or other compound, such as a volatileorganic compound, that serves as a source or precursor for that anion.Examples of electron-withdrawing anions can include, but are not limitedto, sulfate, bisulfate, fluoride, chloride, bromide, iodide,fluorosulfate, fluoroborate, phosphate, fluorophosphate,trifluoroacetate, triflate, fluorozirconate, fluorotitanate,phospho-tungstate, and the like, including mixtures and combinationsthereof. In addition, other ionic or non-ionic compounds that serve assources for these electron-withdrawing anions also can be employed. Itis contemplated that the electron-withdrawing anion can be, or cancomprise, fluoride, chloride, bromide, phosphate, triflate, bisulfate,or sulfate, and the like, or any combination thereof, in some aspectsprovided herein. In other aspects, the electron-withdrawing anion cancomprise sulfate, bisulfate, fluoride, chloride, bromide, iodide,fluorosulfate, fluoroborate, phosphate, fluorophosphate,trifluoroacetate, triflate, fluorozirconate, fluorotitanate, and thelike, or combinations thereof.

In an aspect, the catalyst system can comprise an activator-support, andthe activator-support can comprise fluorided alumina, chlorided alumina,bromided alumina, sulfated alumina, fluorided silica-alumina, chloridedsilica-alumina, bromided silica-alumina, sulfated silica-alumina,fluorided silica-zirconia, chlorided silica-zirconia, bromidedsilica-zirconia, sulfated silica-zirconia, fluorided silica-titania,fluorided silica-coated alumina, sulfated silica-coated alumina,phosphated silica-coated alumina, and the like, as well as any mixtureor combination thereof. In another aspect, the catalyst system cancomprise an activator-support, and the activator-support can comprisefluorided alumina, sulfated alumina, fluorided silica-alumina, sulfatedsilica-alumina, fluorided silica-zirconia, fluorided silica-coatedalumina, sulfated silica-coated alumina, and the like, as well as anymixture or combination thereof.

Commonly used polymerization co-catalysts can include, but are notlimited to, metal alkyl, or organometal, co-catalysts, with the metalencompassing boron, aluminum, and the like. Optionally, the catalystsystems provided herein can comprise a co-catalyst, or a combination ofco-catalysts. For instance, alkyl boron and/or alkyl aluminum compoundsoften can be used as co-catalysts in such catalyst systems.Representative boron compounds can include, but are not limited to,tri-n-butyl borane, tripropylborane, triethylborane, and the like, andthis include combinations of two or more of these materials. While notbeing limited thereto, representative aluminum compounds (e.g.,organoaluminum compounds) can include, trimethylaluminum,triethylaluminum, tri-n-propylaluminum, tri-n-butylaluminum,triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum,diisobutylaluminum hydride, diethylaluminum ethoxide, diethylaluminumchloride, and the like, as well as any combination thereof.

The base resins can be produced using any suitable olefin polymerizationprocess using various types of polymerization reactors, polymerizationreactor systems, and polymerization reaction conditions. As used herein,“polymerization reactor” includes any polymerization reactor capable ofpolymerizing (inclusive of oligomerizing) olefin monomers and comonomers(one or more than one comonomer) to produce homopolymers, copolymers,terpolymers, and the like. The various types of polymerization reactorsinclude those that can be referred to as a batch reactor, slurryreactor, gas-phase reactor, solution reactor, high pressure reactor,tubular reactor, autoclave reactor, and the like, or combinationsthereof. The polymerization conditions for the various reactor types arewell known to those of skill in the art. Gas phase reactors can comprisefluidized bed reactors or staged horizontal reactors. Slurry reactorscan comprise vertical or horizontal loops. High pressure reactors cancomprise autoclave or tubular reactors. Reactor types can include batchor continuous processes. Continuous processes can use intermittent orcontinuous product discharge. Polymerization reactor systems andprocesses also can include partial or full direct recycle of unreactedmonomer, unreacted comonomer, and/or diluent.

A polymerization reactor system can comprise a single reactor ormultiple reactors (2 reactors, more than 2 reactors, etc.) of the sameor different type. For instance, the polymerization reactor system cancomprise a slurry reactor, a gas-phase reactor, a solution reactor, or acombination of two or more of these reactors. Production of polymers inmultiple reactors can include several stages in at least two separatepolymerization reactors interconnected by a transfer device making itpossible to transfer the polymers resulting from the firstpolymerization reactor into the second reactor. The desiredpolymerization conditions in one of the reactors can be different fromthe operating conditions of the other reactor(s). Alternatively,polymerization in multiple reactors can include the manual transfer ofpolymer from one reactor to subsequent reactors for continuedpolymerization. Multiple reactor systems can include any combinationincluding, but not limited to, multiple loop reactors, multiple gasphase reactors, a combination of loop and gas phase reactors, multiplehigh pressure reactors, or a combination of high pressure with loopand/or gas phase reactors. The multiple reactors can be operated inseries, in parallel, or both.

According to one aspect, the polymerization reactor system can compriseat least one loop slurry reactor comprising vertical or horizontalloops. Monomer, diluent, catalyst, and comonomer can be continuously fedto a loop reactor where polymerization occurs. Generally, continuousprocesses can comprise the continuous introduction of monomer/comonomer,a catalyst, and a diluent into a polymerization reactor and thecontinuous removal from this reactor of a suspension comprising polymerparticles and the diluent. Reactor effluent can be flashed to remove thesolid polymer from the liquids that comprise the diluent, monomer and/orcomonomer. Various technologies can be used for this separation stepincluding, but not limited to, flashing that can include any combinationof heat addition and pressure reduction, separation by cyclonic actionin either a cyclone or hydrocyclone, or separation by centrifugation.

A typical slurry polymerization process (also known as the particle formprocess) is disclosed, for example, in U.S. Pat. Nos. 3,248,179,4,501,885, 5,565,175, 5,575,979, 6,239,235, 6,262,191, and 6,833,415,each of which is incorporated herein by reference in its entirety.

Suitable diluents used in slurry polymerization include, but are notlimited to, the monomer being polymerized and hydrocarbons that areliquids under reaction conditions. Examples of suitable diluentsinclude, but are not limited to, hydrocarbons such as propane,cyclohexane, isobutane, n-butane, n-pentane, isopentane, neopentane, andn-hexane. Some loop polymerization reactions can occur under bulkconditions where no diluent is used. An example is polymerization ofpropylene monomer as disclosed in U.S. Pat. No. 5,455,314, which isincorporated by reference herein in its entirety.

According to yet another aspect, the polymerization reactor system cancomprise at least one gas phase reactor (e.g., a fluidized bed reactor).Such reactor systems can employ a continuous recycle stream containingone or more monomers continuously cycled through a fluidized bed in thepresence of the catalyst under polymerization conditions. A recyclestream can be withdrawn from the fluidized bed and recycled back intothe reactor. Simultaneously, polymer product can be withdrawn from thereactor and new or fresh monomer can be added to replace the polymerizedmonomer. Such gas phase reactors can comprise a process for multi-stepgas-phase polymerization of olefins, in which olefins are polymerized inthe gaseous phase in at least two independent gas-phase polymerizationzones while feeding a catalyst-containing polymer formed in a firstpolymerization zone to a second polymerization zone. One type of gasphase reactor is disclosed in U.S. Pat. Nos. 5,352,749, 4,588,790, and5,436,304, each of which is incorporated by reference in its entiretyherein.

According to still another aspect, the polymerization reactor system cancomprise a high pressure polymerization reactor, e.g., can comprise atubular reactor or an autoclave reactor. Tubular reactors can haveseveral zones where fresh monomer, initiators, or catalysts are added.Monomer can be entrained in an inert gaseous stream and introduced atone zone of the reactor. Initiators, catalysts, and/or catalystcomponents can be entrained in a gaseous stream and introduced atanother zone of the reactor. The gas streams can be intermixed forpolymerization. Heat and pressure can be employed appropriately toobtain optimal polymerization reaction conditions.

According to yet another aspect, the polymerization reactor system cancomprise a solution polymerization reactor wherein the monomer/comonomerare contacted with the catalyst composition by suitable stirring orother means. A carrier comprising an inert organic diluent or excessmonomer can be employed. If desired, the monomer/comonomer can bebrought in the vapor phase into contact with the catalytic reactionproduct, in the presence or absence of liquid material. Thepolymerization zone can be maintained at temperatures and pressures thatwill result in the formation of a solution of the polymer in a reactionmedium. Agitation can be employed to obtain better temperature controland to maintain uniform polymerization mixtures throughout thepolymerization zone. Adequate means are utilized for dissipating theexothermic heat of polymerization.

The polymerization reactor system can further comprise any combinationof at least one raw material feed system, at least one feed system forcatalyst or catalyst components, and/or at least one polymer recoverysystem. Suitable reactor systems can further comprise systems forfeedstock purification, catalyst storage and preparation, extrusion,reactor cooling, polymer recovery, fractionation, recycle, storage,loadout, laboratory analysis, and process control. Depending upon thedesired properties of the olefin polymer, hydrogen can be added to thepolymerization reactor as needed (e.g., continuously, pulsed, etc.), andas discussed hereinabove.

Polymerization conditions that can be controlled for efficiency and toprovide desired polymer properties can include temperature, pressure,and the concentrations of various reactants. Polymerization temperaturecan affect catalyst productivity, polymer molecular weight, andmolecular weight distribution. A suitable polymerization temperature canbe any temperature below the de-polymerization temperature according tothe Gibbs Free energy equation. Typically, this includes from about 60°C. to about 280° C., for example, or from about 60° C. to about 110° C.,depending upon the type of polymerization reactor. In some reactorsystems, the polymerization temperature generally can be within a rangefrom about 70° C. to about 90° C., or from about 75° C. to about 85° C.

Suitable pressures will also vary according to the reactor andpolymerization type. The pressure for liquid phase polymerizations in aloop reactor typically can be less than 1000 psig. The pressure for gasphase polymerization can be in the 200 to 500 psig range. High pressurepolymerization in tubular or autoclave reactors generally can beconducted at about 20,000 to 75,000 psig. Polymerization reactors alsocan be operated in a supercritical region occurring at generally highertemperatures and pressures. Operation above the critical point of apressure/temperature diagram (supercritical phase) can offer advantages.

EXAMPLES

The invention is further illustrated by the following examples, whichare not to be construed in any way as imposing limitations to the scopeof this invention. Various other aspects, embodiments, modifications,and equivalents thereof which, after reading the description herein, maysuggest themselves to one of ordinary skill in the art without departingfrom the spirit of the present invention or the scope of the appendedclaims.

Examples 1-9

The LLDPE resin of Example 1 was a commercially-availableethylene/1-hexene copolymer (Chevron Phillips Chemical Company LP)produced using a chromium-based catalyst system. The LLDPE resin ofExample 2 was a commercially-available ethylene/1-hexene copolymer(Chevron Phillips Chemical Company LP) produced using a Ziegler-basedcatalyst system. The LLDPE resin of Example 3 was acommercially-available ethylene/1-hexene copolymer (Chevron PhillipsChemical Company LP) produced using a metallocene-based catalyst system.The LLDPE resin of Example 5 was a commercially-availableethylene/1-hexene copolymer (Chevron Phillips Chemical Company LP)produced using a metallocene-based catalyst system. The properties ofthe polymers of Examples 1-3 and 5 are listed in Table I.

The LLDPE resin of Example 4 was prepared by first dry blending a baseresin (Example 3) with 300 ppm by weight (ppmw) of a masterbatchcontaining a polyethylene carrier resin and 45 wt. % of2,5-dimethyl-2,5-di(t-butylperoxy)hexane. Based on the weight percent ofthe two 0-0 groups in the compound and the 45 wt. % loading inconcentrate, the 300 ppmw loading of the masterbatch in the base resinequates to about 30 ppmw of peroxide groups, based on the weight of thebase resin. The blend of the base resin and peroxide masterbatch wascompounded using a twin screw extrusion system, and then pelletized toform the ethylene/1-hexene copolymer of Example 4. Compounding was doneon a laboratory ZSK-40 twin screw extruder equipped with a melt pump.The extruder was a super compounder with OD/ID ratio of 1.55 and screwL/D ratio of 28.9. Nitrogen purge was used at the extruder feed port.Standard conditions of rate (65 kg/hr), screw speed (230 rpm) and 20mesh filter screen were used, and resulted in a melt temperature ofabout 478° F. and specific energy of 0.13 kW-hr/kg. A 10-hole strand dieplate was used for pelletizing. The pellet count was adjusted to35/gram. The LLDPE resin of Example 6 was prepared as described forExample 4, except that the base resin was Example 5 and the peroxideconcentrate loading was 400 ppmw (about 40 ppmw of peroxide groups basedon the weight of the base resin). The properties of the polymers ofExamples 4 and 6 also are listed in Table I.

As shown in Table I, the polymers of Examples 4 and 6, as compared toExamples 3 and 5, respectively, exhibited an unexpected combination ofproperties: lower MI, lower HLMI, higher HLMI/MI, higher η₀, lower CY-aparameter, and higher LCB content, while the density, peak meltingpoint, vicat softening temperature, and difference between the meltingpoint and the softening temperature (A) were substantially unchanged.The Mn, Mw, Mz, Mw/Mn, and Mz/Mw of the polymers of Examples 4 and 6, ascompared to Examples 3 and 5, respectively, increased only slightly,particularly as compared to the significant changes in the MI, HLMI,HLMI/MI, η₀, CY-a parameter, and LCB content. Thus, the improvement inpolymer melt strength as demonstrated, for example, by the reduction inMI and HLMI and the increase in η₀ and LCB content, was achieved withoutsignificant changes in several other polymer properties.

Table I also demonstrates that the polymers of Examples 4 and 6, ascompared to Examples 1-2, exhibited relatively similar values of η₀,CY-a parameter, and LCB content, and thus would be expected to haverelatively similar melt strengths. However, and unexpectedly, thesesimilar properties were achieved despite the much lower ratios of Mw/Mn,Mz/Mw, and HLMI/MI of Examples 4 and 6 as compared to Examples 1-2, aswell as the lower peak melting point and the smaller difference betweenthe melting point and the softening temperature (A) of Examples 4 and 6.

Table II summarizes certain properties of the polymers of Examples 1-9.The LLDPE resins of Example 7 and Example 8 were prepared as describedfor Example 6, except that the peroxide concentrate loading was 300 ppmwand 600 ppmw, respectively (about 30 ppmw and about 60 ppmw,respectively, of peroxide groups based on the weight of the base resin).The LLDPE resin of Example 9 was a commercially-availableethylene/1-octene copolymer (Dow Chemical Company) produced using aZiegler-based catalyst system and having a nominal 0.905 density. Theunique combination of rheological and thermal properties of the polymersof Examples 4 and 6 are demonstrated in Table II. FIG. 1 illustrates thedynamic rheology properties (viscosity versus shear rate) for thepolymers of Examples 1-8 at 190° C.

Blown film samples were produced from the polymers of Examples 1-4 at a1-mil thickness and a 10-mil thickness, the latter designed to simulatethe performance of thick gauge films up to a film thickness of 100 mils,and above. FIG. 2 is a tensile plot (stress versus strain) for the10-mil blown films of Examples 1-4 in the transverse direction (TD),while FIG. 3 is a tensile plot (stress versus strain) for the 10-milblown films of Examples 1-4 in the machine direction (MD). FIG. 4 is atensile plot (stress versus strain) for the 1-mil blown films ofExamples 1-4 in the transverse direction (TD). Table III summarizescertain properties of the films of Examples 1-4.

FIG. 2 in the TD, unlike FIG. 3 in the MD, illustrates a surprisingdifference in the tensile curves of Example 3-4 as compared to Examples1-2: Examples 3-4 show a non-distinct yield point in the TD, whereasExamples 1-2 show a distinct yield point in the TD followed by sharpdecrease in stress up to an elongation of over 50%. FIG. 4 illustratesthe same difference in tensile curves in the TD for 1-mil films. Thenon-distinct yield point of the films of Examples 3-4 can be importantfor the suitability of thick films that are creased or folded, as filmswith the non-distinct yield point attribute generally do not exhibitfailures in the creased/folded areas as compared to the films ofExamples 1-2. Various measurements from the tensile curves whichnumerically demonstrate the differences between the film properties(stress-strain) of Examples 3-4, as compared to Examples 1-2, aresummarized in Table III.

Table IV provides a comparison of the amount of gels in film samplesproduced from the polymers of Examples 2 and 5-7. Gels were measured on25 micron (1 mil) thick films using an automated camera-based gelcounting machine made by Optical Control System (OCS), Model FS-5. Thesystem consists of a light source and a detector. The film was passedthrough the system, between the light source and the detector, with a150 mm (6 inch) inspection width. A total of 10 square meters of filmarea was inspected and the gels with size greater than 200 microns wereanalyzed. The counts represent the total gels, on a number ofgels/square foot basis, with size >200 micron as detected by the OCSsystem. Surprisingly, both of Examples 6-7 (produced using peroxidetreating) had less gels than that of the commercial ethylene copolymerof Example 2.

TABLE I Property Summary for the Polymers of Examples 1-6 Example 1Example 2 Example 3 Example 4 Example 5 Example 6 Density 0.922 0.9180.916 0.916 0.914 0.914 (g/cc) MI 0.15 0.32 1.45 0.51 0.93 0.33 (g/10min) HLMI 14.5 14.1 24.4 15.7 16.1 10.5 (g/10 min) HLMI/MI 97 44 17 3117 32 Peak Melting 123 126 116 115 115 113 Point (° C.) Vicat Softening108 102 103 103 103 102 Temperature (° C.) Δ Melting − 15 24 13 12 12 11Softening (° C.) Mn 10,800 21,100 43,700 46,200 58,700 59,500 (g/mol) Mw166,000 145,000 108,000 119,000 132,000 142,000 (g/mol) Mz 785,000404,000 191,000 231,000 229,000 255,000 (g/mol) Mw/Mn 15.3 6.9 2.5 2.62.2 2.4 Mz/Mw 4.7 2.8 1.8 1.9 1.7 1.8 η_(o) 985,000 155,000 4,600146,000 7,500 125,000 (Pa-sec) CY-a parameter 0.167 0.174 0.648 0.1310.605 0.168 LCB (per 1000 0.016 0.012 0.002 0.021 0.001 0.012 total Catoms)

TABLE II Properties of Examples 1-9. Peak Vicat Δ Melting SofteningMelting − Exam- η_(o) Point Temperature Softening Density ple (Pa-sec)CY-a (° C.) (° C.) (° C.) (g/cm³) 1 985,000 0.167 123 108 15 0.922 2155,000 0.174 126 102 24 0.918 3 4,600 0.648 116 103 13 0.916 4 146,0000.131 115 103 12 0.916 5 7,500 0.605 115 103 12 0.914 6 125,000 0.168113 102 11 0.914 7 41,200 0.230 — — — — 8 5,660,000 0.093 — — — — 9 — —122 84 38 0.905

TABLE III Film Property Summary for Examples 1-4 Example Example ExampleExample 1 2 3 4 Ratio of: 1.14 1.06 0.980 0.973 Max Stress @ <40% StrainMax Stress @ 40-60% Strain (10 mil film, TD) Ratio of: 1.60 1.24 0.9820.997 Max Stress @ <40% Strain Max Stress @ 40-60% Strain (1 mil film,TD) Slope is negative in the Yes Yes No No 25-50% strain range (10 milfilm, TD) Slope is negative in the Yes Yes No No 25-30% strain range (1mil film, TD) Ratio of: 0.85 0.93 1.06  1.10  Stress @ 50% Strain Stress@ Yield Strain (10 mil film, TD) Ratio of: 0.61 0.84 1.06  0.97  Stress@ 30% Strain Stress @ Yield Strain (1 mil film, TD)

TABLE IV Gel Count Comparison for Examples 2 and 5-7 Example ExampleExample Example 2 5 6 7 Number of gels >200 μm 474 16 78 44 (number perft²)

The invention is described above with reference to numerous aspects andembodiments, and specific examples. Many variations will suggestthemselves to those skilled in the art in light of the above detaileddescription. All such obvious variations are within the full intendedscope of the appended claims. Other embodiments of the invention caninclude, but are not limited to, the following (embodiments aredescribed as “comprising” but, alternatively, can “consist essentiallyof” or “consist of”):

Embodiment 1

An ethylene polymer having a ratio of Mw/Mn of less than or equal toabout 5, a ratio of Mz/Mw of less than or equal to about 2.3, and azero-shear viscosity at 190° C. of greater than or equal to about 8×10⁴Pa-sec.

Embodiment 2

The polymer defined in embodiment 1, wherein the ethylene polymer has amelt index in any range disclosed herein, e.g., from 0 to about 2, from0 to about 1, from about 0.05 to about 1, from about 0.1 to about 0.8g/10 min, etc.

Embodiment 3

The polymer defined in any one of embodiments 1-2, wherein the ethylenepolymer has a ratio of HLMI/MI in any range disclosed herein, e.g., fromabout 15 to about 50, from about 20 to about 50, from about 20 to about45, from about 25 to about 35, etc.

Embodiment 4

The polymer defined in any one of embodiments 1-3, wherein the ethylenepolymer has a density in any range disclosed herein, e.g., from about0.895 to about 0.928, from about 0.90 to about 0.925, from about 0.905to about 0.925, from about 0.91 to about 0.92 g/cm³, etc.

Embodiment 5

The polymer defined in any one of embodiments 1-4, wherein the ethylenepolymer has a zero-shear viscosity at 190° C. in any range disclosedherein, e.g., from about 8×10⁴ to about 2×10⁶, from about 1×10⁵ to about1×10⁶, from about 1×10⁵ to about 8×10⁵, from about 1×10⁵ to about 5×10⁵Pa-sec, etc.

Embodiment 6

The polymer defined in any one of embodiments 1-5, wherein the ethylenepolymer has a ratio of Mw/Mn in any range disclosed herein, e.g., fromabout 2 to about 5, from about 2 to about 4, from about 2 to about 3.5,from about 2 to about 3, from about 2.1 to about 2.8, from about 2.1 toabout 2.7, etc.

Embodiment 7

The polymer defined in any one of embodiments 1-6, wherein the ethylenepolymer has a ratio of Mz/Mw in any range disclosed herein, e.g., fromabout 1.5 to about 2.3, from about 1.5 to about 2.2, from about 1.5 toabout 2.1, from about 1.5 to about 2, etc.

Embodiment 8

The polymer defined in any one of embodiments 1-7, wherein the ethylenepolymer has a Mw in any range disclosed herein, e.g., from about 75,000to about 250,000, from about 85,000 to about 200,000, from about 90,000to about 150,000, from about 100,000 to about 150,000 g/mol, etc.

Embodiment 9

The polymer defined in any one of embodiments 1-8, wherein the ethylenepolymer has a Mn in any range disclosed herein, e.g., from about 10,000to about 70,000, from about 25,000 to about 70,000, from about 30,000 toabout 70,000, from about 35,000 to about 65,000 g/mol, etc.

Embodiment 10

The polymer defined in any one of embodiments 1-9, wherein the ethylenepolymer has a Mz in any range disclosed herein, e.g., from about 175,000to about 300,000, from about 200,000 to about 300,000, from about210,000 to about 290,000 g/mol, etc.

Embodiment 11

The polymer defined in any one of embodiments 1-10, wherein the ethylenepolymer has a reverse comonomer distribution, e.g., the number of shortchain branches (SCB's) per 1000 total carbon atoms of the polymer at Mwis greater than at Mn, etc.

Embodiment 12

The polymer defined in any one of embodiments 1-11, wherein the ethylenepolymer has a number of long chain branches (LCB) per 1000 total carbonatoms in any range disclosed herein, e.g., from about 0.008 to about0.04, from about 0.009 to about 0.035, from about 0.01 to about 0.03LCB, etc.

Embodiment 13

The polymer defined in any one of embodiments 1-12, wherein the ethylenepolymer has a peak melting point of less than or equal to about 120° C.,e.g., in a range from about 100 to about 120° C., in a range from about110 to about 120° C., etc.

Embodiment 14

The polymer defined in any one of embodiments 1-13, wherein the ethylenepolymer has a vicat softening temperature of greater than or equal toabout 95° C., e.g., in a range from about 100 to about 120° C., in arange from about 100 to about 110° C., in a range from about 95 to about105° C., etc.

Embodiment 15

The polymer defined in any one of embodiments 1-14, wherein the ethylenepolymer has a difference between the peak melting point of the polymerand the vicat softening temperature of the polymer of less than or equalto about 20° C., e.g., less than or equal to about 18° C., less than orequal to about 16° C., less than or equal to about 14° C., etc.

Embodiment 16

The polymer defined in any one of embodiments 1-15, wherein the ethylenepolymer has a CY-a parameter at 190° C. in any range disclosed herein,e.g., from about 0.08 to about 0.28, from about 0.09 to about 0.25, fromabout 0.1 to about 0.2, from about 0.1 to about 0.18, etc.

Embodiment 17

The polymer defined in any one of embodiments 1-16, wherein the ethylenepolymer is an ethylene/α-olefin copolymer.

Embodiment 18

The polymer defined in any one of embodiments 1-17, wherein the ethylenepolymer is an ethylene/1-butene copolymer, an ethylene/1-hexenecopolymer, or an ethylene/1-octene copolymer.

Embodiment 19

The polymer defined in any one of embodiments 1-18, wherein the ethylenepolymer is an ethylene/1-hexene copolymer.

Embodiment 20

The polymer defined in any one of embodiments 1-19, wherein the ethylenepolymer is produced by a process comprising contacting a base resin witha peroxide compound at a temperature sufficient to generate peroxidegroups at 10-50 ppm of peroxide groups based on the weight of the baseresin.

Embodiment 21

The polymer defined in embodiment 20, wherein the step of contacting thebase resin with the peroxide compound comprises melt processing a blend(or mixture) of the base resin and the peroxide compound at any meltprocessing temperature disclosed herein, e.g., in a range from about 120to about 300° C., in a range from about 150 to about 250° C., in a rangefrom about 175 to about 225° C., etc.

Embodiment 22

The polymer defined in embodiment 21, wherein the melt processing isperformed in a twin screw extrusion system.

Embodiment 23

The polymer defined in embodiment 21, wherein the melt processing isperformed in a single screw extrusion system.

Embodiment 24

The polymer defined in any one of embodiments 20-23, wherein the baseresin has a melt index in any range disclosed herein, e.g., from 0 toabout 5, from about 0.25 to about 2, from about 0.5 to about 2.5, fromabout 0.5 to about 2 g/10 min, etc.

Embodiment 25

The polymer defined in any one of embodiments 20-24, wherein the baseresin has a ratio of HLMI/MI in any range disclosed herein, e.g., fromabout 10 to about 35, from about 10 to about 30, from about 10 to about25, from about 15 to about 30, etc.

Embodiment 26

The polymer defined in any one of embodiments 20-25, wherein the baseresin has a density in any range disclosed herein, e.g., from about0.895 to about 0.928, from about 0.90 to about 0.925, from about 0.905to about 0.925, from about 0.91 to about 0.92 g/cm³, etc.

Embodiment 27

The polymer defined in any one of embodiments 20-26, wherein the baseresin has a zero-shear viscosity at 190° C. in any range disclosedherein, e.g., from about 2×10³ to about 7×10⁴, from about 3×10³ to about5×10⁴, from about 2×10³ to about 2×10⁴, from about 3×10³ to about 2×10⁴Pa-sec, etc.

Embodiment 28

The polymer defined in any one of embodiments 20-27, wherein the baseresin has a ratio of Mw/Mn in any range disclosed herein, e.g., fromabout 2 to about 5, from about 2 to about 4, from about 2 to about 3.5,from about 2 to about 3, from about 2.1 to about 2.8, from about 2.1 toabout 2.7, etc.

Embodiment 29

The polymer defined in any one of embodiments 20-28, wherein the baseresin has a ratio of Mz/Mw in any range disclosed herein, e.g., fromabout 1.5 to about 2.3, from about 1.5 to about 2.2, from about 1.5 toabout 2.1, from about 1.5 to about 2, etc.

Embodiment 30

The polymer defined in any one of embodiments 20-29, wherein the baseresin has a Mw in any range disclosed herein, e.g., from about 75,000 toabout 250,000, from about 85,000 to about 200,000, from about 90,000 toabout 150,000, from about 100,000 to about 150,000 g/mol, etc.

Embodiment 31

The polymer defined in any one of embodiments 20-30, wherein the baseresin has a Mn in any range disclosed herein, e.g., from about 10,000 toabout 70,000, from about 25,000 to about 70,000, from about 30,000 toabout 70,000, from about 35,000 to about 65,000 g/mol, etc.

Embodiment 32

The polymer defined in any one of embodiments 20-31, wherein the baseresin has a Mz in any range disclosed herein, e.g., from about 165,000to about 300,000, from about 175,000 to about 300,000, from about200,000 to about 290,000 g/mol, etc.

Embodiment 33

The polymer defined in any one of embodiments 20-32, wherein the baseresin has a reverse comonomer distribution, e.g., the number of shortchain branches (SCB's) per 1000 total carbon atoms of the polymer at Mwis greater than at Mn, etc.

Embodiment 34

The polymer defined in any one of embodiments 20-33, wherein the baseresin has less than about 0.008 long chain branches (LCB) per 1000 totalcarbon atoms, e.g., less than about 0.005 LCB, less than about 0.003LCB, etc.

Embodiment 35

The polymer defined in any one of embodiments 20-34, wherein the baseresin has a peak melting point of less than or equal to about 120° C.,e.g., in a range from about 100 to about 120° C., in a range from about110 to about 120° C., etc.

Embodiment 36

The polymer defined in any one of embodiments 20-35, wherein the baseresin has a vicat softening temperature of greater than or equal toabout 95° C., e.g., in a range from about 100 to about 120° C., in arange from about 100 to about 110° C., in a range from about 95 to about105° C., etc.

Embodiment 37

The polymer defined in any one of embodiments 20-36, wherein the baseresin has a difference between the peak melting point of the base resinand the vicat softening temperature of the base resin of less than orequal to about 20° C., e.g., less than or equal to about 18° C., lessthan or equal to about 16° C., less than or equal to about 14° C., etc.

Embodiment 38

The polymer defined in any one of embodiments 20-37, wherein the baseresin has a CY-a parameter at 190° C. in any range disclosed herein,e.g., from about 0.4 to about 0.8, from about 0.5 to about 0.8, fromabout 0.4 to about 0.7, from about 0.5 to about 0.7, etc.

Embodiment 39

The polymer defined in any one of embodiments 20-38, wherein the baseresin is produced using a metallocene-based catalyst system.

Embodiment 40

The polymer defined in any one of embodiments 20-39, wherein the baseresin is produced using a metallocene-based catalyst system comprising ametallocene compound and an activator, e.g., any metallocene compoundand any activator disclosed herein.

Embodiment 41

The polymer defined in embodiment 40, wherein the activator comprises anactivator-support, an aluminoxane compound, an organoboron ororganoborate compound, an ionizing ionic compound, or any combinationthereof.

Embodiment 42

The polymer defined in any one of embodiments 40-41, wherein theactivator comprises an activator-support, the activator-supportcomprising a solid oxide treated with an electron-withdrawing anion.

Embodiment 43

The polymer defined in any one of embodiments 40-41, wherein theactivator comprises an aluminoxane compound.

Embodiment 44

The polymer defined in any one of embodiments 40-43, wherein themetallocene-based catalyst system further comprises a co-catalyst.

Embodiment 45

The polymer defined in any one of embodiments 40-44, wherein themetallocene-based catalyst system further comprises an organoaluminumco-catalyst.

Embodiment 46

The polymer defined in any one of embodiments 20-45, wherein the baseresin is produced in any reactor disclosed herein, e.g., a slurryreactor, a gas-phase reactor, a solution reactor, etc., as well asmulti-reactor combinations thereof.

Embodiment 47

An article of manufacture comprising the ethylene polymer defined in anyone of embodiments 1-46.

Embodiment 48

A film comprising the ethylene polymer defined in any one of embodiments1-47, e.g. a blown film, a cast film, etc.

Embodiment 49

A film comprising the ethylene polymer defined in any one of embodiments1-47 and at least one additive.

Embodiment 50

The film defined in embodiment 49, wherein the additive comprises anantioxidant, acid scavenger, antiblock additive, slip additive,colorant, filler, processing aid, UV inhibitor, or any combinationthereof.

Embodiment 51

A method of making a film (e.g., a blown film, a cast film, etc.)comprising an ethylene polymer, the method comprising:

(i) providing an ethylene polymer defined in any one of embodiments1-46; and

(ii) melt processing the ethylene polymer through a film die (e.g., ablown film die, a cast film die, etc.) to form the film.

Embodiment 52

The method defined in embodiment 51, wherein the method comprises meltprocessing the ethylene polymer and at least one additive through thedie.

Embodiment 53

The method defined in embodiment 52, wherein the additive comprises anantioxidant, acid scavenger, antiblock additive, slip additive,colorant, filler, processing aid, UV inhibitor, or any combinationthereof.

Embodiment 54

The method defined in any one of embodiments 51-53, wherein the ethylenepolymer is produced by a process comprising contacting any base resindisclosed herein with a peroxide compound at a temperature sufficient togenerate peroxide groups at 10-50 ppm of peroxide groups based on theweight of the base resin.

Embodiment 55

The method defined in embodiment 54, wherein the step of contacting thebase resin with the peroxide compound comprises melt processing a blend(or mixture) of the base resin and the peroxide compound at any meltprocessing temperature disclosed herein, e.g., in a range from about 120to about 300° C., in a range from about 150 to about 250° C., in a rangefrom about 175 to about 225° C., etc.

Embodiment 56

A film formed by the method defined in any one of embodiments 51-55,e.g., a blown film, a cast film, etc.

Embodiment 57

The film or method defined in any one of embodiments 48-56, wherein thefilm has a thickness in any range disclosed herein, e.g., from about 1to about 200 mils, from about 10 to about 200 mils, from about 30 toabout 120 mils, from about 40 to about 100 mils, etc.

Embodiment 58

The film or method defined in any one of embodiments 48-57, wherein, ina stress versus strain curve in the transverse direction (TD) for a10-mil film (e.g., a blown film, a cast film), a ratio of the maximumstress at a strain of less than 40% to the maximum stress at a strain inthe 40% to 60% range is in any range of ratios disclosed herein, e.g.,less than or equal to 1, less than or equal to about 0.99, less than orequal to about 0.98, from about 0.85 to 1, from about 0.9 to about 0.99,from about 0.9 to about 0.98, etc.

Embodiment 59

The film or method defined in any one of embodiments 48-58, wherein, ina stress versus strain curve in the transverse direction (TD) for a1-mil film (e.g., a blown film, a cast film), a ratio of the maximumstress at a strain of less than 40% to the maximum stress at a strain inthe 40% to 60% range is in any range of ratios disclosed herein, e.g.,less than or equal to 1.1, less than or equal to about 1, less than orequal to about 0.99, less than or equal to about 0.98, from about 0.85to 1.1, from about 0.9 to about 1, from about 0.9 to about 0.99, etc.

Embodiment 60

The film or method defined in any one of embodiments 48-59, wherein, ina stress versus strain curve in the transverse direction (TD) for a10-mil film, the slope is not negative in the 25% to 50% strain range,and/or in a stress versus strain curve in the transverse direction (TD)for a 1-mil film, the slope is not negative in the 25% to 30% strainrange.

Embodiment 61

The film or method defined in any one of embodiments 48-60, wherein, ina stress versus strain curve in the transverse direction (TD) for a10-mil film, the stress at 50% strain is greater than the stress at theyield point.

Embodiment 62

The film or method defined in any one of embodiments 48-61, wherein, ina stress versus strain curve in the transverse direction (TD) for a1-mil film, a ratio of the stress at a strain of 30% to the stress atthe yield point is in any range of ratios disclosed herein, e.g.,greater than or equal to 0.9, greater than or equal to about 0.95, in arange from 0.9 to about 1.2, in a range from 0.9 to about 1.1, in arange from about 0.95 to about 1.2, in a range from about 0.95 to about1.1, etc.

Embodiment 63

The film or method defined in any one of embodiments 48-62, wherein thefilm is a blown film.

Embodiment 64

The film or method defined in any one of embodiments 48-62, wherein thefilm is a cast film.

The invention claimed is:
 1. A method of making a film comprising anethylene polymer, the method comprising: (i) providing an ethylenepolymer having a ratio of Mw/Mn of less than or equal to about 5, aratio of Mz/Mw of less than or equal to about 2.3, and a zero-shearviscosity at 190° C. of greater than or equal to about 1×10⁵ Pa-sec;wherein the ethylene polymer is further characterized by a peak meltingpoint in a range from about 100 to about 120° C., a vicat softeningtemperature in a range from about 95 to about 110° C., and a differencebetween the peak melting point and the vicat softening temperature ofless than or equal to about 16° C.; and (ii) melt processing theethylene polymer through a film die to form the film.
 2. The method ofclaim 1, wherein: the method comprises melt processing the ethylenepolymer and at least one additive through the die; and the ethylenepolymer is an ethylene/α-olefin copolymer.
 3. The method of claim 2,wherein the film is a blown film.
 4. The method of claim 3, wherein theethylene/α-olefin copolymer is produced by a process comprising meltprocessing a mixture of a base resin and a peroxide compound in a twinscrew extrusion system at a temperature in a range from about 120 toabout 300° C. to generate peroxide groups at about 10-50 ppm of peroxidegroups based on the weight of the base resin.
 5. The method of claim 1,wherein the ethylene polymer is further characterized by: a melt indexin a range from about 0.05 to about 2; a ratio of HLMI/MI in a rangefrom about 15 to about 50; and a density in a range from about 0.895 toabout 0.928 g/cm³.
 6. The method of claim 1, wherein: the ratio of Mw/Mnis in a range from about 2 to about 5; and the ratio of Mz/Mw is in arange from about 1.5 to about 2.3.
 7. The method of claim 6, wherein thezero-shear viscosity at 190° C. is in a range from about 1×10⁵ to about2×10⁶ Pa-sec.
 8. The method of claim 7, wherein the film is a blown filmor a cast film, and is characterized by a thickness in a range fromabout 0.5 to about 250 mils.
 9. The blown film or cast film prepared bythe method of claim
 8. 10. A method of making a film comprising anethylene/α-olefin copolymer, the method comprising: (i) providing anethylene/α-olefin copolymer having: a ratio of Mw/Mn in a range fromabout 2 to about 4; a ratio of Mz/Mw in a range from about 1.5 to about2.2; a melt index in a range from 0 to about 1; a zero-shear viscosityat 190° C. of greater than or equal to about 1×10⁵ Pa-sec; a density ina range from about 0.91 to about 0.92 g/cm³; and from about 0.008 toabout 0.04 long chain branches (LCB) per 1000 total carbon atoms; and(ii) melt processing the ethylene/α-olefin copolymer through a film dieto form the film.
 11. The method of claim 10, wherein the copolymer isfurther characterized by: a peak melting point in a range from about 105to about 120° C.; and a vicat softening temperature in a range fromabout 95 to about 110° C.
 12. The method of claim 10, wherein thecopolymer is further characterized by a CY-a parameter at 190° C. in arange from about 0.08 to about 0.28.
 13. The method of claim 10,wherein: the ethylene/α-olefin copolymer is produced by a processcomprising melt processing a mixture of a base resin and a peroxidecompound at a weight ratio of peroxide groups of the peroxide compoundin a range from about 10 to about 60 ppm, based on the weight of thebase resin; and step (ii) comprises melt processing theethylene/α-olefin copolymer and at least one additive through the filmdie to form the film.
 14. The method of claim 10, wherein the film is ablown film or a cast film, and is characterized by a thickness in arange from about 0.5 to about 250 mils.
 15. The blown film or cast filmprepared by the method of claim
 14. 16. A method of making a filmcomprising an ethylene/1-hexene copolymer, the method comprising: (i)providing an ethylene/1-hexene copolymer having: a ratio of Mw/Mn ofless than or equal to about 5; a ratio of Mz/Mw of less than or equal toabout 2.3; a zero-shear viscosity at 190° C. of greater than or equal toabout 1×10⁵ Pa-sec; a CY-a parameter at 190° C. in a range from about0.08 to about 0.28; and a density in a range from about 0.905 to about0.925 g/cm³; and (ii) melt processing the ethylene/1-hexene copolymerthrough a film die to form the film.
 17. The method of claim 16,wherein: the ratio of Mw/Mn is in a range from about 2 to about 3.5; andthe ratio of Mz/Mw is in a range from about 1.5 to about 2.2.
 18. Themethod of claim 17, wherein: the CY-a parameter at 190° C. is in a rangefrom about 0.08 to about 0.18; or the zero-shear viscosity at 190° C. isin a range from about 1×10⁵ to about 2×10⁶ Pa-sec; or both.
 19. Themethod of claim 17, wherein the film is a blown film or a cast film, andis characterized by a thickness in a range from about 0.5 to about 250mils.
 20. The blown film or cast film prepared by the method of claim19.
 21. A method of making a film comprising an ethylene/α-olefincopolymer, the method comprising: (i) providing an ethylene/α-olefincopolymer having a ratio of Mw/Mn of less than or equal to about 5, aratio of Mz/Mw of less than or equal to about 2.3, and a zero-shearviscosity at 190° C. of greater than or equal to about 1×10⁵ Pa-sec;wherein the ethylene/α-olefin copolymer is further characterized by aCY-a parameter at 190° C. in a range from about 0.08 to about 0.28, orfrom about 0.008 to about 0.04 long chain branches (LCB) per 1000 totalcarbon atoms, or both, and a density in a range from about 0.895 toabout 0.928 g/cm³, and (ii) melt processing the ethylene/α-olefincopolymer through a film die to form the film.
 22. The method of claim21, wherein: the ratio of Mw/Mn is in a range from about 2 to about 5;the ratio of Mz/Mw is in a range from about 1.5 to about 2.3; and thezero-shear viscosity at 190° C. is in a range from about 1×10⁵ to about2×10⁶ Pa-sec.
 23. The method of claim 22, wherein the ethylene/α-olefincopolymer is further characterized by: a melt index in a range fromabout 0.05 to about 2; and a ratio of HLMI/MI in a range from about 15to about
 50. 24. The method of claim 22, wherein the film is a blownfilm or a cast film, and is characterized by a thickness in a range fromabout 0.5 to about 250 mils.
 25. The blown film or cast film prepared bythe method of claim 24.